Unable to block specific devices

OK so after days and days of going back and forth following one xfinity link after another, I have come to the conclusion that Xfinity has now made it impossible to block specific devices that are stealing your WiFi. Wow thanks guys. I can pause a device but that doesn't actually do a dam thing. So can I just get free WiFi to since I'm apparently paying for my whole dam neighborhood. I really hate Xfinity and if there was any other internet service providers worth a dam I'd cancel my service ASAP!